Notes: This engine replaces the 2001-2007 Chevy 6.0L LQ4 engine. ECM MUST BE TUNED, not doing so can damage the engine. A PCV valve must be ran. You must also run an Air-Oil separator system such as the Moroso #85487 to capture the excess crankcase vapors LS engines are known for. If you are not running a MAP Sensor, the MAP timing option in the timing control box must be zeroed out all the way across. Failure to do so will allow the controller to add timing which can lead to detonation. You must also run some sort of a steam line kit that dumps to your water pump, radiator or radiator hose; we recommend a 4 corner setup like the Trick Flow #TFS-306SB601. This allows air pockets/hot spots to escape the heads and can also be used to purge out trapped air when filling the radiator for the first time.